Unmanned security system is used mainly as a control method for connecting and operating the automation machines and the machines of a security post installed in a vast number of houses or high-rises. In addition, the system is devised to find the infiltrators who break into a house or a building unexpectedly or find out the outbreak of a fire at an early stage.
This system is also a system which can supervise through a monitor displayed in a remote place by connecting the fire sensors into a computer in the gates or the windows through which it is very easy for the trespassers to break into, or the district in which are vulnerable to a fire or the area in which the fire is easily perceptible.
As an example of the unmanned security system, there is a Time Lapse Video Tape Recorder which is used for monitoring and an observation for a long time to prevent the thefts, and is installed in the important areas such as banks, museums and so on. This recorder does not record all the frames of the video video transmitted from outside imaging apparatus in real-time manner, but records 1 frame at every regular time interval selected from the transmitted video videos in real-time while repeating a progressing and a stop of a recorded tape by a capstan motor of a recording section. In addition, even when reproducing the video signal recorded in a recording tape, this system controls the capstan motor of the recording section and reads an video frame recorded in the recording tape while progressing a tape by an video frame unit. The recording and reproduction of said video frame are performed by an user according to a set input time mode at regular time interval, and thereby the intermittent recording and reproduction of the video signal have been accomplished.
There was a problem that the operator of said apparatus for recording and reproducing a video needs to change the recorded tape periodically, which is very troublesome, and time-consuming, and also needs to purchase an additional equipment for performing special functions such as multi-recording and division of reproduced videos.
In order to solve these problems, a DVR (Digital Video Recorder) which does not use a recording tape of analog system but uses a storage medium of a digital system is developed. This DVR records a video into a storage medium such as a memory in a digital form and reproduces it, and whereby the recorded data can be maintained substantially semi-permanently without damaging the recording medium. Besides, it is a very expensive equipment by which the special functions such as multi-recording and division of reproduced videos can be performed without installing any additional equipments outside.
In such digital video recording apparatus, setting a recording mode and a frame per a second can be performed by an user. Of the recording mode, there are a general continuous mode, a recording mode created by sensing of the movement, and a recording mode created by sensing of a sensor. When setting a recording frame per a second for each mode, generally, four kinds of methods are set as follows. There are a low speed mode in which a recording speed is 5 frame per a second, a middle speed mode in which a recording speed is 9 frame per a second, a high speed mode in which a recording speed is 20 frame per a second, and a super-high speed mode in which a recording speed is 30 frame per a second.
Here, a motion detection mode which is a recording mode of the digital video recording apparatus is the recording mode for adjusting and then detecting the brightness and darkness of a video data captured by a camera in case of the trespass of the infiltrators while the unmanned security system is operating, and movement sensitivity of the brightness and darkness. Since the motion detection mode is a very important function in the unmanned security system which is used as a digital recording apparatus, the recording speed is generally set as the super-high speed mode.
But, in case of above-mentioned motion detection mode, the recording can be performed according to a preceding setting. Therefore, even though a number of frames can be obtained when the preceding setting is the super-high speed mode, there is a problem that the storage capacity of the storage medium is getting larger. When the preceding setting a general mode, it is possible to increase the data amount which can be stored in a storage medium, but there is a problem it is not possible to provide the important videos (for example, the information about an infiltrator) in detail. In addition, there is a problem that the brightness and darkness can not be distinguished due to an obscure video, or a suspect can avoid the motion detection recording mode by taking lower attitudes than sensitivity of the movement of the motion detection mode.